A. Field of the Invention
This invention relates to the field of computerized techniques for orthodontic treatment planning for human patients. More particularly, the invention is directed to a method and system for a comprehensive evaluation of total care of orthodontic patients comprising evaluation of available treatment options, evaluation of a proposed treatment plan, as well as evaluation of the progress during the course of the treatment, thereby helping the practitioner or the user in making treatment adjustments if necessary for finding a desired treatment plan or during the course of the treatment. An interactive workstation and associated computerized techniques for facilitating integration of various tasks performed in planning and evaluation of treatment for orthodontic patients is disclosed.
B. Description of Related Art
The traditional process of diagnosis and treatment planning for a patient with orthodontic problems or disease typically consists of the practitioner obtaining clinical history, medical history, dental history, and orthodontic history of the patient supplemented by 2D photographs, 2D radiographic images, CT scans, 2D and 3D scanned images, ultrasonic scanned images, and in general non-invasive and sometimes invasive images, plus video, audio, and a variety of communication records. Additionally, physical models, such as made from plaster of paris, of the patient's teeth are created from the impressions taken of the patient's upper and lower jaws. Such models are manually converted into teeth drawings by projecting teeth on drawing paper. Thus, there is a large volume of images and data involved in the diagnosis and treatment planning process. Furthermore, the information may require conversion from one form to another and selective reduction before it could become useful. There are some computerized tools available to aid the practitioner in these data conversion and reduction steps, for example to convert cephalometric x-rays (i.e., 2 dimensional x-ray photographs showing a lateral view of the head and jaws, including teeth) into points of interest with respect to soft tissue, hard tissue, etc., but they are limited in their functionalities and scope. Even then, there is a fairly substantial amount of manual work involved in these steps.
Additionally, a number of measurements, e.g., available space between teeth, are also often done manually. Generally, these steps are time consuming and prone to inherent inaccuracies. Furthermore, the practitioner has to contend with the biological interdependencies within the patient, which introduces constraints eliminating certain treatment options that would otherwise be acceptable, between the soft tissue, the hard tissue, and the teeth. There is lack of an integrated platform which a practitioner could utilize to filter-out non-practicable treatment options.
Consequently, the practitioner is left to mental visualization, chance process to select the treatment course that would supposedly work. Furthermore, the diagnosis process is some-what ad-hoc and the effectiveness of the treatment depends heavily upon the practitioner's level of experience. Often, due to the complexities of the detailed steps and the time consuming nature of them, some practitioners take a shortcut, relying predominantly on their intuition to select a treatment plan. For example, the diagnosis and treatment planning is often done by the practitioner on a sheet of acetate placed over the X-rays. All of these factors frequently contribute towards trial and error, hit-and-miss, lengthy and inefficient treatment plans that require numerous mid-course adjustments. While at the beginning of treatment things generally run well as all teeth start to move at least into the right direction, at the end of treatment a lot of time is lost by adaptations and corrections required due to the fact that the end result has not been properly planned at any point of time. By and large, this approach lacks reliability, reproducibility and precision. More over, there is no comprehensive way available to a practitioner to stage and simulate the treatment process in advance of the actual implementation to avoid the often hidden pitfalls. And the patient has no choice and does not know that treatment time could be significantly reduced if proper planning was done.
In recent years, computer-based approaches have been proposed for aiding orthodontists in their practice. However, these approaches are limited to diagnosis and treatment planning of craniofacial structures, including the straightening of teeth. See Andreiko, U.S. Pat. No. 6,015,289; Snow, U.S. Pat. No. 6,068,482; Kopelmann et al., U.S. Pat. No. 6,099,314; Doyle, et al., U.S. Pat. No. 5,879,158; Wu et al., U.S. Pat. No. 5,338,198, and Chisti et al., U.S. Pat. Nos. 5,975,893 and 6,227,850, the contents of each of which is incorporated by reference herein. Also see imaging and diagnostic software and other related products marketed by Dolphin Imaging, 6641 Independence Avenue, Canoga Park, Calif. 91303-2944.
A method for generation of a 3D model of the dentition from an in-vivo scan of the patient, and interactive computer-based treatment planning for orthodontic patients, is described in published PCT patent application of OraMetrix, Inc., the assignee of this invention, publication no. WO 01/80761, the contents of which are incorporated by reference herein.
Other background references related to capturing three dimensional models of dentition and associated craniofacial structures include S. M. Yamany and A. A. Farag, “A System for Human Jaw Modeling Using Intra-Oral Images” in Proc. IEEE Eng. Med. Biol. Soc. (EMBS) Conf, Vol. 20, Hong Kong, October 1998, pp. 563-566; and M. Yamany, A. A. Farag, David Tasman, A. G. Farman, “A 3-D Reconstruction System for the Human Jaw Using a Sequence of Optical Images,” IEEE Transactions on Medical Imaging, Vol. 19, No. 5, May 2000, pp. 538-547. The contents of these references are incorporated by reference herein.
The technical literature further includes a body of literature describing the creation of 3D models of faces from photographs, and computerized facial animation and morphable modeling of faces. See, e.g., Pighin et al., Synthesizing Realistic Facial Expression from Photographs, Computer Graphics Proceedings SIGGRAPH '98, pp. 78-94 (1998); Pighin et al., Realistic Facial Animation Using Image-based 3D Morphing, Technical Report no. UW-CSE-97-01-03, University of Washington (May 9, 1997); and Blantz et al., A Morphable Model for The Synthesis of 3D Faces, Computer Graphics Proceedings SIGGRAPH '99 (August, 1999). The contents of these references are incorporated by reference herein.
However, a comprehensive evaluation of total care of orthodontic patients comprising evaluation of available treatment options, evaluation of a proposed treatment plan, as well as evaluation of the progress during the course of the treatment, in terms of the overall quality of treatment, by and large, remains subjective, cumbersome, not reproducible, error prone and limited in scope. Generally the evaluation is done at either the beginning of the treatment or at the end of the treatment; and lacks continuous monitoring and improvement of the treatment as and when needed.
PAR Index, reported by Richmond S, Shaw W C, O'Brien K D et al., “The development of PAR Index (Peer Assessment rating): reliability and validity,” Eur J Orthod 1992; 14: 125-40, offers an approach to evaluating the degree or severity of mal-occlusion of a patient. The evaluation is primarily useful in performing diagnosis of an orthodontic patient. The evaluation is done by inspection of the dentition of a patient and general observation regarding the patient's condition. The evaluation utilizes 2D photographs of the patient's dentition. The process generally comprises evaluation of the occlusal contact points, degree of over jet or over byte, malocclusion classification, etc. The evaluation is manual and subject to judgment and error.
The American Board of Orthodontics (ABO) has introduced an Objective Grading System (OGS) for evaluating the results of an orthodontic treatment once it is completed. OGS evaluates the dental casts and panoramic radiographs using eight criteria; namely, alignment, marginal ridges, buccolingual inclination, occlusal relationships, occlusal contacts, overjet, interproximal contacts, and root angulation; and a method of scoring teh adequacy. (a) Alignment refers to an assessment of tooth alignment. In the anterior region, the incisal edges and lingual surfaces of the maxillary anterior teeth and the incisal edges and labial-incisal surfaces of the mandibular anterior teeth are chosen to assess anterior alignment. These are not only the functioning areas of these teeth, but they also influence esthetics if they are not arranged in proper relationship. In the maxillary posterior region, the mesiodistal central groove of the premolars and molars is used to assess adequacy of alignment. In the mandibular arch, the buccal cusps of the premolars and molars are used to assess proper alignment. (b) Marginal ridges are used to assess proper vertical positioning of the posterior teeth. In patients with no restorations, minimal attrition, and no periodontal bone loss, the marginal ridges of adjacent teeth should be at the same level. If the marginal ridges are at the same relative height, the cementoenamel junctions will be at the same level. In a periodontally healthy individual, this will result in flat bone level between adjacent teeth. In addition, if marginal ridges are at the same height, it will be easier to establish proper occlusal contacts, since some marginal ridges provide contact areas for opposing cusps. (c) Buccolingual inclination is used to assess the buccolingual angulation of the posterior teeth. In order to establish proper occlusion in maximum intercuspation and avoid balancing interferences, there should not be a significant difference between the heights of the buccal and lingual cusps of the maxillary and mandibular molars and premolars. (d) Occlusal relationship is used to assess the relative anteroposterior position of the maxillary and mandibular posterior teeth. The buccal cusps of the maxillary molars, premolars, and canines must align within 1 mm of the interproximal embrasures of the mandibular posterior teeth. The mesiobuccal cusp of the maxillary first molar must align within 1 mm of the buccal groove of the mandibular first molar. (e) Occlusal contacts are measured to assess the adequacy of the posterior occlusion. Again, a major objective of orthodontic treatment is to establish maximum intercuspation of opposing teeth. Therefore, the functioning cusps are used to assess the adequacy of this criterion; i.e., the buccal cusps of the mandibular molars and premolars, and the lingual cusps of the maxillary molars and premolars. If cusp form is small or diminutive, that cusp is not scored. (f) Overjet is used to assess the relative transverse relationship of the posterior teeth, and the anteroposterior relationship of the anterior teeth. In the posterior region, the mandibular buccal cusps and maxillary lingual cusps are used to determine proper position within the fossae of the opposing arch. In the anterior region, the mandibular incisal edges should be in contact with the lingual surfaces of the maxillary anterior teeth. (g) Interproximal contacts are used to determine if all spaces within the dental arch have been closed. Persistent spaces between teeth after orthodontic therapy are not only unesthetic, but can lead to food impaction. (h) Root angulation is used to assess how well the roots of the teeth have been positioned relative to one another. Although the panoramic radiograph is not the perfect record for evaluating root angulation, it is probably the best means possible for making this assessment. If roots are properly angulated, then sufficient bone will be present between adjacent roots, which could be important if the patient were susceptible to periodontal bone loss at some point in time. If roots are dilacerated, then they are not graded. As mentioned earlier, the OGS requires dental casts and its application is limited to evaluating the post-treatment results. The OGS in its present form cannot be used to evaluate the effectiveness of a proposed orthodontic treatment and the adjustments thereto in order to realize a desired treatment plan prior to actually embarking upon execution of the treatment plan. The ABO has developed an orthodontic measuring gauge to assist in the manual measurement of parameters related to the OGS criteria from the dental cast and the panoramic radiograph. Although the measuring gauge introduces a degree of consistency in the measurements when performed by different people, the evaluation is still limited in scope to two-dimensional analysis.
The Institute of Medicine's Committee on Quality of Health Care in America, in a year 2001 report on “Crossing the Quality Chasm: A New Health System for the 21st Century,” has suggested that a comprehensive quality management system should include measures of: (a) treatment efficiency, (b) treatment effectiveness, (c) Patient connectedness to treatment, (d) timeliness of treatment, (e) treatment safety and (f) treatment equitability. However, to-date there dose not exist a comprehensive system or a set of measuring tools in the field of orthodontics that would enable a practitioner to evaluate these six dimensions of the quality of care while planning and throughout delivery of treatment to orthodontic patients.
What is lacking in the art is a an integrated treatment evaluation and quality measurement approach in the field of orthodontics that is either automatic or semi-automatic, objective, reproducible, reliable, accurate and enables measurements in two-dimensions or three-dimensions. In addition what is lacking in the art is an evaluation and measurement process in orthodontics that enables total quality improvement of the treatment planning and delivery process through periodic feedback. What is further lacking in the art is a treatment evaluation process that enables continuous learning from the patients' responses to different treatment approaches, thereby enabling establishments of improved benchmarks for standard of care. The present invention discloses solutions to these and other problems of treatment evaluation and is directed to an effective, computer-based, integrated and interactive orthodontic treatment planning andevaluation system that provides the necessary tools to allow the orthodontist to quickly and efficiently design and evaluate the treatment plan and delivery for a patient.